The present invention relates to an organic nonlinear optical material. Such a material can be utilized as a material for nonlinear optical elements, such as waveguides and the like, which constitute optically functional devices, such as electrooptical devices, all optical devices and the like, for use in optical communication, optical computer and the like.
Since nonlinear optical materials are those showing second-order or third-order nonlinear optical response in electric field of light and have functions such as amplification, oscillation, wavelength conversion, refractive index conversion and the like, they are said to be a fundamental material for optical communication, optical computer and the like. Inter alia, nonlinear optical materials showing third-order nonlinear optical response display nonlinear refractive index effect and optical bistability, and hence, they are expected to be applied to high-speed optical switch, optical logical element, optical memory and the like.
However, the conventional organic nonlinear optical materials are excellent in high-speed responsiveness as compared with inorganic materials but have small third-order nonlinear optical properties. As a result, they have been hardly applied to the aforementioned devices. For example, organic nonlinear optical materials described in Hachiro Nakanishi and Shuji Okada, "Third-order Nonlinear Optical Materials and Their Applications", O plus E, 1996, No. 4, pages 68-74 have small third-order nonlinear optical constant .chi..sup.(3) of 10.sup.-10 to 10.sup.-12 esu as obtained by third harmonic generation measurement and have not been applied to electrooptical devices, all optical devices and the like for use in optical communication, optical computer and the like. In addition, since the aforementioned .chi..sup.3 values are those obtained by utilizing the resonance state of molecules, there is a problem on the thermal stability of the materials. Thus, it is difficult to permanently use the organic nonlinear optical material in the above-mentioned elements. Further, since the conventional organic nonlinear optical materials exhibit a great light absorption in the visible region, the application of the materials to the aforementioned elements is unsuitable due to their large light transmission loss.
As described above, there is a problem that since the conventional organic nonlinear optical materials have small nonlinear optical constants, such nonlinear optical constants are those obtained by utilizing the resonance state of molecules and the materials themselves exhibit a great light absorption in the visible region, they have not been applied to electrooptical devices, all optical devices and the like for use in optical communication, optical computer and the like.
In view of the foregoing, it is an object of the present invention to provide an organic nonlinear optical material which has nonlinear optical properties superior to those of the conventional organic nonlinear optical materials and which can be applied to electrooptical devices, all optical devices and the like for use in optical communication, optical computer and the like.
Another object of the present invention to provide a nonlinear optical element using the organic nonlinear optical material.
Still another object of the present invention to provide a nonlinear optical device using the nonlinear optical element.